Whereas the formulation of powdered, bleach-containing detergent and cleaning agents no longer presents any problems today, the formulation of stable liquid, bleach-containing detergents and cleaning agents continues to represent a problem. Because of the customary absence of the bleaching agent in liquid detergents and cleaning agents, stains that are normally removed particularly because of the present bleaching agents are accordingly often removed only in an inadequate manner. A similar problem also exists for bleach-free color detergents, in which the bleaching agent is omitted in order to protect the dyes in the textile and to prevent them from being bleached. In the absence of the bleaching agent, a further complication is that, instead of the removal of so-called bleachable stains that are normally removed at least partially by the peroxygen-based bleaching agent, on the contrary, the stain is often even intensified or made more difficult to remove as a result of the washing process; this might be attributed not least to initiated chemical reactions, which, for example, can consist of the polymerization of certain dyes present in the stains.
Such problems occur in particular with stains containing polymerizable substances. The polymerizable substances are principally polyphenolic dyes, preferably flavonoids, in particular from the class of anthocyanidins or anthocyans. The stains can have been caused in particular by food products or beverages that contain corresponding dyes. The stains can be in particular spots caused by fruits or vegetables or red wine spots as well which contain polyphenolic dyes in particular, principally those from the class of anthocyanidins or anthocyans.
For example, the use of gallic acid esters such as propyl gallate in detergents and washing agents to improve the removal of stains containing polymerizable substances is known from the international patent application WO 2011/023716 A1.
The use of 4-pyridinones substituted at the N atom optionally with organic groups, such as methyl, ethyl, propyl, phenyl, naphthyl, or carboxyethyl groups, for removing stains from textiles is known from the international patent application WO 2007/042140 A2.
The dimer of kojic acid and its chelation property for iron was described by R. C. Fox and P. D. Taylor in Bioorganic & Medicinal Chem. Lett. 8 (1998), 443-446.
It has now been found surprisingly that the washing or cleaning performance of the detergent or cleaning agent can be considerably improved particularly in regard to bleachable stains by using the kojic acid dimer and analogous bis-pyranonylmethanes.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.